Methods, systems, and devices for wireless communications are described that provide for concurrent reference signal transmissions using common resources, such as demodulation reference signal (DMRS) transmissions, from a number of non-orthogonal multiple access (NOMA) transmitters. Different transmitters may use different sequences for reference signal transmissions, which may allow a receiver, such as a wireless base station, to decode the reference signal transmissions for each NOMA transmitter and perform channel estimation for each NOMA transmitter. The reference signal transmissions may be asynchronous with a bounded timing offset or quasi-synchronous, and the reference signal sequence selection may provide for relatively reliable channel estimation and coherent demodulation.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A method for wireless communication, comprising: receiving, from a base station, an indication of a set of resources for transmission of a reference signal, wherein a plurality of non-orthogonal multiple access (NOMA) transmitters are configured for at least partially concurrent transmissions using the set of resources; identifying, based at least in part on the set of resources, a plurality of short sequences to be included in the reference signal, each short sequence of the plurality of short sequences having a root index and cyclic shift that provides a cross-correlation with other of the plurality of short sequences that is below a threshold value; concatenating the plurality of short sequences to generate a reference signal sequence for the reference signal; and transmitting the reference signal to the base station.
2. The method of claim 1 , wherein the set of resources comprise frequency resources and time resources, and wherein a first short sequence of the plurality of short sequences is applied to a first subset of the frequency resources that are located within a first subset of the time resources, and a second short sequence of the plurality of short sequences is applied to a second subset of the frequency resources that are located within a second subset of the time resources.
3. The method of claim 1 , wherein the identifying the plurality of short sequences comprises: determining the root index and cyclic shift for each short sequence within a plurality of frequency domain resources; and mapping each of the plurality of short sequences to each of a corresponding plurality of time domain resources.
4. The method of claim 1 , wherein the plurality of short sequences each comprise a portion of a linear block code that can be successfully decoded if an error in receiving one or more portions of the linear block code occurs.
5. The method of claim 4 , wherein the linear block code is an error-correcting code.
6. The method of claim 1 , wherein the threshold value is based at least in part on a one or more of a cell radius of the base station, a multipath delay spread associated with the base station, or any combination thereof.
7. The method of claim 1 , wherein the reference signal sequence allows for asynchronous reference signal transmissions from multiple transmitters.
8. The method of claim 1 , wherein the identifying the plurality of short sequences comprises: identifying, based at least in part on the set of resources, a codebook containing a set of short sequences; and selecting a subset of the set of short sequences as the plurality of short sequences based at least in part on a user equipment (UE) identification.
9. The method of claim 1 , wherein each short sequence of the plurality of short sequences is a constant-amplitude zero-autocorrelation (CAZAC) sequence, a pseudo-random noise (PN) sequence, a Kasami sequence, or a Golay sequence.
10. An apparatus for wireless communication, comprising: means for receiving, from a base station, an indication of a set of resources for transmission of a reference signal, wherein at least one non-orthogonal multiple access (NOMA) transmitter associated with the apparatus is configured for at least partially concurrent transmissions using the set of resources; means for identifying, based at least in part on the set of resources, a plurality of short sequences to be included in the reference signal, each short sequence of the plurality of short sequences having a root index and cyclic shift that provides a cross-correlation with other of the plurality of short sequences that is below a threshold value; means for concatenating the plurality of short sequences to generate a reference signal sequence for the reference signal; and means for transmitting the reference signal to the base station.
11. The apparatus of claim 10 , wherein the set of resources comprise frequency resources and time resources, and wherein a first short sequence of the plurality of short sequences is applied to a first subset of the frequency resources that are located within a first subset of the time resources, and a second short sequence of the plurality of short sequences is applied to a second subset of the frequency resources that are located within a second subset of the time resources.
12. The apparatus of claim 10 , wherein the means for the identifying the plurality of short sequences determines the root index and cyclic shift for each short sequence within a plurality of frequency domain resources, and maps each of the plurality of short sequences to each of a corresponding plurality of time domain resources.
13. The apparatus of claim 10 , wherein the plurality of short sequences each comprise a portion of a linear block code that can be successfully decoded if an error in receiving one or more portions of the linear block code occurs.
14. The apparatus of claim 10 , wherein the means for the identifying the plurality of short sequences identifies, based at least in part on the set of resources, a codebook containing a set of short sequences, and selects a subset of the set of short sequences as the plurality of short sequences based at least in part on a user equipment (UE) identification.
15. The apparatus of claim 10 , wherein each short sequence of the plurality of short sequences is a constant-amplitude zero-autocorrelation (CAZAC) sequence, a pseudo-random noise (PN) sequence, a Kasami sequence, or a Golay sequence.
16. An apparatus for wireless communication, comprising: a processor; memory in electronic communication with the processor; and instructions stored in the memory and executable by the processor to cause the apparatus to: receive, from a base station, an indication of a set of resources for transmission of a reference signal, wherein at least one non-orthogonal multiple access (NOMA) transmitter associated with the apparatus is configured for at least partially concurrent transmissions using the set of resources; identify, based at least in part on the set of resources, a plurality of short sequences to be included in the reference signal, each short sequence of the plurality of short sequences having a root index and cyclic shift that provides a cross-correlation with other of the plurality of short sequences that is below a threshold value; concatenate the plurality of short sequences to generate a reference signal sequence for the reference signal; and transmit the reference signal to the base station.
17. The apparatus of claim 16 , wherein the set of resources comprise frequency resources and time resources, and wherein a first short sequence of the plurality of short sequences is applied to a first subset of the frequency resources that are located within a first subset of the time resources, and a second short sequence of the plurality of short sequences is applied to a second subset of the frequency resources that are located within a second subset of the time resources.
18. The apparatus of claim 16 , wherein the instructions to cause the apparatus to identify the plurality of short sequences comprise instructions to cause the apparatus to: determine the root index and cyclic shift for each short sequence within a plurality of frequency domain resources; and map each of the plurality of short sequences to each of a corresponding plurality of time domain resources.
19. The apparatus of claim 16 , wherein the plurality of short sequences each comprise a portion of a linear block code that can be successfully decoded if an error in receiving one or more portions of the linear block code occurs.
20. The apparatus of claim 19 , wherein the linear block code is an error-correcting code.
21. The apparatus of claim 16 , wherein the threshold value is based at least in part on a one or more of a cell radius of the base station, a multipath delay spread associated with the base station, or any combination thereof.
22. The apparatus of claim 16 , wherein the reference signal sequence allows for asynchronous reference signal transmissions from multiple transmitters.
23. The apparatus of claim 16 , wherein the instructions to cause the apparatus to identify the plurality of short sequences comprise instructions to cause the apparatus to: identify, based at least in part on the set of resources, a codebook containing a set of short sequences; and select a subset of the set of short sequences as the plurality of short sequences based at least in part on a user equipment (UE) identification.
24. The apparatus of claim 16 , wherein each short sequence of the plurality of short sequences is a constant-amplitude zero-autocorrelation (CAZAC) sequence, a pseudo-random noise (PN) sequence, a Kasami sequence, or a Golay sequence.
25. A non-transitory computer-readable medium storing code for wireless communication, the code comprising instructions executable by a processor to: receive, from a base station, an indication of a set of resources for transmission of a reference signal, wherein at least one non-orthogonal multiple access (NOMA) transmitter operatively coupled to the processor is configured for at least partially concurrent transmissions using the set of resources; identify, based at least in part on the set of resources, a plurality of short sequences to be included in the reference signal, each short sequence of the plurality of short sequences having a root index and cyclic shift that provides a cross-correlation with other of the plurality of short sequences that is below a threshold value; concatenate the plurality of short sequences to generate a reference signal sequence for the reference signal; and transmit the reference signal to the base station.
26. The non-transitory computer-readable medium of claim 25 , wherein the set of resources comprise frequency resources and time resources, and wherein a first short sequence of the plurality of short sequences is applied to a first subset of the frequency resources that are located within a first subset of the time resources, and a second short sequence of the plurality of short sequences is applied to a second subset of the frequency resources that are located within a second subset of the time resources.
27. The non-transitory computer-readable medium of claim 25 , wherein the code comprising instructions to identify the plurality of short sequences further comprises instructions to determine the root index and cyclic shift for each short sequence within a plurality of frequency domain resources, and maps each of the plurality of short sequences to each of a corresponding plurality of time domain resources.
28. The non-transitory computer-readable medium of claim 25 , wherein the plurality of short sequences each comprise a portion of a linear block code that can be successfully decoded if an error in receiving one or more portions of the linear block code occurs.
29. The non-transitory computer-readable medium of claim 25 , wherein the code comprising instructions to identify the plurality of short sequences further comprises instructions to identify, based at least in part on the set of resources, a codebook containing a set of short sequences, and selects a subset of the set of short sequences as the plurality of short sequences based at least in part on a user equipment (UE) identification.
30. The non-transitory computer-readable medium of claim 25 , wherein each short sequence of the plurality of short sequences is a constant-amplitude zero-autocorrelation (CAZAC) sequence, a pseudo-random noise (PN) sequence, a Kasami sequence, or a Golay sequence.
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January 31, 2019
December 8, 2020
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